MONITORING OF FAST-GROWING VOLCANO IN SOVIET IS DISCUSSED

By WALTER SULLIVAN, Special to the New York Times

Published: January 22, 1987

HILO, Hawaii, Jan. 21—
So voluminous are the outpourings of lava from the Klyuchevskaya volcano on the Kamchatka Peninsula in the Soviet Union that specialists there have concluded that the entire mountain, 15,675 feet high, has formed in the last 7,000 years.

Apart from the Hawaiian volcanoes, which erupt frequently but do not form steep-sided mountains, Mount Klyuchevskaya appears to produce more lava than any other volcano on earth, according to S. A. Fedotov, director of the Institute of Volcanology in Petropavlovsk.

He described results from prolonged monitoring of this remote volcano near Alaska and its five companion volcanoes to an international meeting on volcanology being held here this week at the University of Hawaii. Volcano's Extraordinary Growth

Dr. Fedotov said in an interview that Klyuchevskaya produced one quarter of the lava erupted by all 68 volcanoes in the 1,600-mile Kurile-Kamchatka chain, which would explain the volcano's extraordinarily rapid growth.

Other volcanoes in the chain, which stretches southwest into Japan, erupt far less often and voluminously.

The Klyuchevskaya volcanoes are of special interest to American volcanologists because one of them, Bezymyanny, has an eruptive history strikingly similar to that of Mount St. Helens. Since a cataclysmic explosion in the 1950's blew off the top and one side of Byezimyanny, it has been rebuilding its conic structure; it has also exploded intermittently.

This is seen as an ominous precedent by Dr. Donald A. Swanson, director of the Davis A. Johnston Cascade Observatory in Vancouver, Wash., which is responsible for monitoring Mount St. Helens. Soviet Volcano Called Worrisome

The most recent eruption at Mount St. Helens occurred in May 1986. Although there is no indication that it will explode again, the example of Bezymyanny is worrisome, Dr. Swanson said.

In June 1980, after its devastating eruption a month earlier, a lava dome in Mount St. Helens began building on its crater floor. In July it was destroyed by a violent eruption. A new dome began growing, but in October it too was blown sky high.

Since then a third dome has been gradually evolving through small eruptions but there have been no further great explosions. Bezymyanny, on the other hand, has erupted more than a dozen times.

Predicting dome-building eruptions inside the St. Helens crater has become fairly straightforward, Dr. Swanson said. The dome begins swelling two to three weeks in advance, as recorded by electronic tiltmeters mounted in pairs on the dome. Monitoring Inside Crater

Seismic devices on the dome and crater floor record tremors induced as lava moves up into the dome. Virtually all monitoring of Mount St. Helens is done inside its crater, Dr. Swanson said.

Laser pulses aimed at reflectors on the dome and elsewhere in the crater also record local deformatiom of the terrain as do strain meters mounted in the dome's cracks.

Readings from all these devices are transmitted to the observatory in nearby Vancouver.

A puzzling feature of the Klyucheskaya volcanoes, according to Dr. Swanson, is the manner in which Bezymyanny differs from the others. It produces a lava that is sticky and plugs the volcano until it explodes. The other volcanoes erupt lava that hardens into rock, or basalt.

According to Dr. Fedotov, in the 215 years before his institute was founded in 1935, the summit of Klyuchevskaya erupted 38 times, in most cases explosively. Three times its summit was blown off, only to rebuild itself.

Eleven times in the past half century the volcano has erupted from its flank, in addition to a number of summit eruptions, Dr. Fedotov said. Flank eruptions, like the one from St. Helens, can be particularly destructive.